“Hysteria” centers on Dr. Logan Harlow (Suvari), a bright but socially awkward neurologist/psychiatrist who travels home to Austin, Texas, to investigate a mysterious epidemic among high school girls that may be spreading through technology.

Knight will play her brother Carter James Harlow, who has been on death row since he was 19 and is two months away from execution.

He tries to convince his sister that the panic in Austin is the same hysteria that sent him to prison 25 years ago — and that if she’ll agree to help exonerate him, he’ll give her the clues she needs to solve the crisis.

It marks the first starring role for Knight since his “Grey’s” character Dr. George O’Malley was killed off in 2009. Since then, his TV credits have been limited to a guest spot on “Law & Order: SVU” and an arc as a political wunderkind on “The Good Wife” in 2013.